1. Field of the Invention
The present invention relates to a hybrid recording and/or reproducing apparatus and a recording and/or reproducing method which are applied suitably to video recording and/or reproducing apparatus and the like that are required to record and preserve a large quantity of video and audio information and read out the stored information at a high readout speed.
More particularly, the invention relates to a hybrid recording and/or reproducing apparatus and a recording and/or reproducing method which are designed to save for the backup purpose records of a magnetic disk (hard disk), semiconductor memory, optical disk or magneto-optical disk (will be termed generically xe2x80x9cdisk recording mediumxe2x80x9d hereinafter) onto a tape recording medium so that in the event of readout failure of all or part of a record on the disk recording medium, the record in the state before the occurrence of readout failure can be restored on the disk recording medium based on the backup record, the apparatus and method also allowing the expansion of the recording capacity as the whole system based on the combination of the disk recording medium and tape recording medium.
2. Description of the Prior Art
In recent years, there have been developed video recording and/or reproducing apparatus used in broadcasting stations and the like in which audio/video signals (digital information) are recorded onto a disk recording medium such as a hard disk at the production of a broadcast program and the record on the recording medium is reproduced at the time of broadcasting.
The disk recording medium used by these video recording and/or reproducing apparatus has a recording capacity as large as several giga-bits and has the ability of information erasion and rewriting and high-speed readout, so that it is suitable for recording and editing information of each complete broadcast program which is broadcast in a tight schedule.
On the other hand, however, the disk recording medium is susceptible to external impact and vibration, and moreover it is more expensive in terms of unit recording capacity as compared with the conventional tape recording medium. The durability of the disk recording medium in long-term use and its usable life time are not yet known. Another problem of the disk recording medium left unsolved is how to deal with the emergence of accidental failure, e.g., data read error.
On this account, two recording mediums including active one and spare one are prepared for the enhanced reliability of operation in most cases.
The recording and/or reproducing apparatus which uses the disk recording medium treats records based on index information which indicates the range of recording area used or control information called xe2x80x9cfile systemxe2x80x9d.
It is desirable obviously for broadcasting stations and the like to preserve all records including video and audio information of broadcast programs produced in the past so that the video and audio information can be reproduced afterward in accordance with the control information. However, preserving all records on the disk recording medium, which is more expensive in terms of unit recording capacity than the tape recording medium, is not practical.
Although a conceivable manner for recording and preserving a large quantity of video and audio information is increasing the number of disk recording mediums run by one recording and/or reproducing apparatus, it will incur an increased medium cost and increased unexpected disk troubles. The control information in the recording and/or reproducing apparatus can possibly fail by some cause, which may cause a disk failure e.g., data read error, resulting possibly in a retrieval failure of all or part of the recorded information.
Recording/reproduction apparatus using semiconductor memories (except for some kinds of semiconductor memories) have their memory records lost if the power supply is shut off.
Accordingly, it is an object of the present invention to provide a hybrid recording and/or reproducing apparatus and recording and/or reproducing method which are capable of dealing with the readout failure of all or part of a record on a disk recording medium by restoring the record in the state before the occurrence of failure on the disk recording medium based on the backup record which has been saved on a tape recording medium, the apparatus and method also allowing the expansion of the recording capacity as the whole system based on the combination of the disk recording medium and tape recording medium.
In order to achieve the above objective, the inventive hybrid recording and/or reproducing apparatus for recording and/or reproducing digital information including an audio and/or video signal comprises first recording and/or reproducing means which records and/or reproduces the digital information on a nonlinear-access recording medium, second recording and/or reproducing means which records and/or reproduces the digital information on a tape recording medium having a recording capacity which is greater than or equal to the recording capacity of the nonlinear-access recording medium, and control means which controls the first and second recording and/or reproducing means such that same digital information as the digital information recorded on the nonlinear-access recording medium is recorded onto the tape recording medium simultaneously to or on expiration of a certain time after the recording of the digital information onto the nonlinear-access recording medium.
In the inventive hybrid recording and/or reproducing apparatus, the control means monitors records of digital information on the disk recording medium, and in the event of readout failure of all or part of a record on the disk recording medium by some cause, the backup digital information corresponding to the missing record portion is read out of the tape recording medium and recorded onto the disk recording medium automatically so that the record in the state before the occurrence of failure is restored on the disk recording medium.
Accordingly, the inventive apparatus has enhanced reliability for keeping digital information including audio/video signals and computer-based graphic information as compared with conventional recording and/or reproducing apparatus having only disk recording mediums.